A tremendous variety of devices used today rely on actuators of one sort or another to convert electrical energy to mechanical energy. Conversely, many power generation applications operate by converting mechanical action into electrical energy. Employed to harvest mechanical energy in this fashion, the same type of device may be referred to as a generator. Likewise, when the structure is employed to convert physical stimulus such as vibration or pressure into an electrical signal for measurement purposes, it may be characterized as a sensor. Yet, the term “transducer” may be used to generically refer to any of the devices.
A number of design considerations favor the selection and use of advanced dielectric elastomer materials, also referred to as “electroactive polymers”, for the fabrication of transducers. These considerations include potential force, power density, power conversion/consumption, size, weight, cost, response time, duty cycle, service requirements, environmental impact, etc. As such, in many applications, electroactive polymer technology offers an ideal replacement for piezoelectric, shape-memory alloy and electromagnetic devices such as motors and solenoids.
An electroactive polymer transducer comprises two electrodes having deformable characteristics and separated by a thin elastomeric dielectric material. When a voltage difference is applied to the electrodes, the oppositely charged electrodes attract each other thereby compressing the polymer dielectric layer therebetween. As the electrodes are pulled closer together, the dielectric polymer film becomes thinner (the Z-axis component contracts) as it expands in the planar directions (along the X- and Y-axes), i.e., the displacement of the film is in-plane. The electroactive polymer film may also be configured to produce movement in a direction orthogonal to the film structure (along the Z-axis), i.e., the displacement of the film is out-of-plane. For example, U.S. Pat. No. 7,567,681 discloses electroactive polymer film constructs which provide such out-of-plane displacement—also referred to as surface deformation or as thickness mode deflection.
The material and physical properties of the electroactive polymer film may be varied and controlled to customize the deformation undergone by the transducer. More specifically, factors such as the relative elasticity between the polymer film and the electrode material, the relative thickness between the polymer film and electrode material and/or the varying thickness of the polymer film and/or electrode material, the physical pattern of the polymer film and/or electrode material (to provide localized active and inactive areas), the tension or pre-strain placed on the electroactive polymer film as a whole, and the amount of voltage applied to or capacitance induced upon the film may be controlled and varied to customize the features of the film when in an active mode.
Numerous applications exist that benefit from the advantages provided by such electroactive polymer films whether using the film alone or using it in an electroactive polymer actuator. One of the many applications involves the use of electroactive polymer transducers as actuators to produce haptic, tactile, vibrational feedback (the communication of information to a user through forces applied to the user's body), and the like, in user interface devices. There are many known user interface devices which employ such feedback, typically in response to a force initiated by the user. Examples of user interface devices that may employ such feedback include keyboards, keypads, game controller, remote control, touch screens, computer mice, trackballs, stylus sticks, joysticks, etc. The user interface surface can comprise any surface that a user manipulates, engages, and/or observes regarding feedback or information from the device. Examples of such interface surfaces include, but are not limited to, a key (e.g., keys on a keyboard), a game pad or buttons, a display screen, etc.
Use of electroactive polymer materials in consumer electronic media devices as well as the numerous other commercial and consumer applications highlights the need to increase production volume and reduce manufacturing cost. There is a need for methods to easily and quickly install electroactive polymer devices. In addition, like incandescent light bulbs, dielectric elastomer transducers occasionally burn out and need to be replaced. It is desirable to minimize the time, effort, and expense required to replace them. Also, it is sometimes desirable to situate actuators directly on a printed circuit board. This can eliminate costs of cables and connectors, and save space. The art discloses many approaches to making electrical and mechanical connections to dielectric elastomer transducers. U.S. Pat. No. 7,915,789 B2, for example, discloses the use of machine screws to make both the electrical and mechanical connections. In U.S. Pat. No. 7,940,476 B2, the electrical connections are made with a conventional flex cable and the mechanical connections are made with screw fasteners. These approaches in the art have some drawbacks. A screwdriver is required to tighten the machine screws in U.S. Pat. No. 7,915,789 B2 which can loosen with use to cause an unreliable electrical contact. The costs of the flex cable and connectors disclosed in U.S. Pat. No. 7,940,476 B2 can be significant.
The present disclosure provides electrical interconnects, such as quick-connect terminals, for dielectric elastomer transducers. The electrical interconnects enable the transducer to be electrically coupled to external systems. The terminals provide both electrical and mechanical connection. A non-limiting illustration of a quick-connect dielectric elastomer transducer is provided by terminals that interface the dielectric elastomer transducer with male connector pins.